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Trailer Brake Question.

Discussion in 'Trucks and Trailers' started by FearThisDeere, Jul 7, 2006.

  1. FearThisDeere

    FearThisDeere LawnSite Bronze Member
    Messages: 1,154

    I bought a used 21 ft. car trailer the other day in CT. and towed it home. There are brakes on both Dexter axles. The truck I towed it home with does not have a brake controller, but I of course I plugged in the 7 round connector for the lights. About 30 miles into my trip there was a rest area and as normal when I pull a trailer, I pull over and just check everything out. The first thing that I noticed was that there was smoke coming from my front right wheel. I leaned in and you could smell the brakes. I felt the other three wheels and they felt warm as well. So, at this point I was a little worried. I unplugged the trailer, backed it up and put the truck in neutral. The trailer did not stop the truck, so the brakes were probably not on. I drove for another few miles and checked the wheels and they were cooler. By the time I got home they were back to normal. So, what it the world happened? The only thing that I could thinm of was that when I picked up the trailer, the light plug was corroded, so the owner had filed it down. Could that have caused a problem? Does it need to be filed down more? Would corrosion cause a short circut like this. Any ideas would be greatly appreciated.
  2. grass_cuttin_fool

    grass_cuttin_fool LawnSite Gold Member
    Messages: 3,526

    Some times corrosion will let current jump or arc to another circuit if they are close. I would take the plug off and maybe relace it, once they start to corrode up, it's hard to stop it. I worked as a truck mechanic and we ran the north east, we kept CRC spray handy all the time and would keep the plugs lubed all the time but with all the salt and sand from the winters they would still corrode up. You may have it .........but I have a link to a neet website that has the 6 and 7 way wiring diagrams and also the 4 way. well heck i will post the site for anyone that may need or want to save it to your favorites, the 7 way plug is at the bottum of the page


  3. FearThisDeere

    FearThisDeere LawnSite Bronze Member
    Messages: 1,154

    Thanks Wayne. I actually used that site to help me wire a couple of trailers. Anyone else have any ideas?
  4. BSDeality

    BSDeality LawnSite Silver Member
    Messages: 2,849

    the problem with 6/7 plugs is they are not standardized. When I last rented an equipment trailer I picked up a 6 to 7 way adapter for my truck. The trailer came with center pin electric brake, and my truck has center pin aux. When we hooked it up the brakes were coming on without touching the brakes because of this. The adapter was reconfigurable, but still was a pain that I had to change it.
  5. FearThisDeere

    FearThisDeere LawnSite Bronze Member
    Messages: 1,154

    OK, I kind of get what you are saying, but I did not have an adapter. The trailer plug went straight into the stock truck plug. Would that make a difference?
  6. out4now

    out4now LawnSite Bronze Member
    from AZ
    Messages: 1,796

    I'll ask around at work, we sell Dexter Axles and Brake controllers. See if anyone knows. Most likely it was a short circuit by what I've read so far but that is without seeing it.
  7. xcopterdoc

    xcopterdoc LawnSite Senior Member
    Messages: 752

    Even if you run without an adapter, there are still two ways to wire a 7 way plug. Center as the AUX or center as the brake. Depends on how the truck and the trailer are wired. Years ago DOT stepped in and standardized all the over the road trucks and trailers as far as wiring went. All plugs, wire colors ect are standardized. Not so with privately owned trailers.
  8. FearThisDeere

    FearThisDeere LawnSite Bronze Member
    Messages: 1,154

    So here is a dumb question: Is there a way to pull the center pin out of the current setup and replace it with a newer one or do I have to rewire the whole plug??
  9. oldrustycars

    oldrustycars LawnSite Senior Member
    Messages: 301

    there is a standard to how these plugs should be wired, but nothing is stopping someone from wiring it however they want. the blue terminal should be for trailer brakes. someone could have put the brake wire in the trailer plug to, for example, the left turn terminal. then every time you put the turn signal on in the truck, the trailer brakes would apply, and go on and off with the signal. also, the inside of the plug could be a mess, with corrosion causing loose wires to contact other terminals.
  10. BSDeality

    BSDeality LawnSite Silver Member
    Messages: 2,849

    its easy enough to take the plug apart, usually only one screw. you just have to reverse the aux and electric brake wires

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